Submerged-melt welding and composition therefor



} 3,100,829 I SUBMERGED-MELT WELDING-AND COMPOSITION THEREFOR Filed Ja 5, 1961 I I AugLIS, 1963 R. KUBLI' EfAL 2 Sheets-Sheet 1 v u 23 ug fifi .22] ommmmuum 3 5&3

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10m OO v Q INVENTORS ROBERT A.KUBL| WILLIAM'B. SHARAV ATTORNEY- Aug. 13, 1963 Filed Jan. 3, 1961 R. A. KUBLI ETAL 3,100,829 SUBMERGED-MELT WELDING AND COMPOSITION THEREFOR 2 Sheets-Sheet 2 FT-LBS CHARPY V IMPACT STRENGTH 5O TEMPERATURE DEGREES F POWER 7 SOURCE"'16 TWERLSBNG INVENTORSI ROBERT A. KUBLI I WILLIAM B. SHARAV ATTORNE V a f r I 3,160,829 7 SUBMERGED-MELT WELDING AND 'CGMIOSITION "rnnn nnon Robert A. Kubli, Scotch Plains, and wnnamn. fihtiiav,

United States Patent Short Hills, NJ assignors to Union Carbide Corpora- I tion, a corporation of New York I Filed Jan. 3, 1961, SraNo. 80,221

' '7, Claims. ((Il. 21--'73) 'I he invention relates to. submerged-melt Welding, and particularly to improved welding compositions for making steel welds having high-impact properties even at low tempenatures.

Patent No. 2,043,960,"involves the deposition of metal fnom a bare consumable electrode rod'or' wire under a blanket-otgranular welding composition I Such process ha 'been widely accepted by virtueof advantages including speed, tavonalble properties, and mechanization. 'Acoording'rto the present invention there is provided Submerged-arc or melt welding, as disclosed in US.

a novel granular submerged-melt welding composition that contains the t olloiwing ingredients:

The invention also provides a method of submergedarc welding of high-impact steel which comprises feeding a con-sumable steel"electrode tow ardjthe work-in-circuitice Patented Aug. l3, 19%3 to increase metal depositionr ates. 7 At relatively high welding current'values commercially available bonded fluxes seem to break down and do not form a properly protective shielding slag. With fused compositions, however,

the current capacity is much greater and, therefore the utility of the welding process is extended by our invention.

Prior to the present invention there has. been no commercially available fused welding composition which met modern impact requirements. LindesfUnionmelt Grade 80 (US. Patent Nos. 2,200,737 .and 2,228,639)

has customarily been used where good impactproperties are desired, but it is not completely adequate. A serious economic result of this, as an example, is in the building 'of submarines with HY-SO steel.

mergedarc welding in the past has been used extensively in shipbuilding because of its relatively low cost and consistently high quality. However, because of the lack of a suitable composition, such process could not be used "in welcling sumbarines madewith HY-SO steel.

As a consequence, coatedstick electrodes, manually applied, have oi? necessity been used at great economic sacrifice.

The invention fills this urgent need; i v

, The primary object ot this invention is to provide a 'fused submerged-melt welding composition that" is capable of successfully producing high quality welded joints 7 having the ability to withstand relatively high-impact lforces, especially at relatively low temperatures. Another object 1 8110 provide a welding composition for arse with alloyed welding-Wires which renders the weld chemistry relatively independent of arc voltage fluctuations and stillpnovides, the alloy content required to attain specific tensile levels rfior specific steels.

v -A further object is to provide a fused composition to be welded under-a.blanket-ofgranular submerged-melt I welding composition composed of tused 'CaO and SiO in which the CaO/ SiO ratio ranges between 0.80- and 1.8.: Industrial requirements for .weldments in.

structural't'ype steels such as H 80, T-l, and nickel alloy steels demand ,greater'impactproperties at lower temperatures than weieheretofore possible; Such weldments as pressure vessels,- ;.bridges,' and heavy structure s, pamticuliarly subjected to relatively low "temperatures, re!

tain relatively high-impact properties. I

(bnv

consistentlyfland satisfamorily produce-welds having highimpactpnopenties, T his.-is so, atleast in part, because quire asaprerequisite joined steel members which'maintional bondedwelding. compositions do not such compositions are usually provided with-an alloying L withqwelding conditions and is especially sensitive'. to

vo ltagegfluctuations More generally;however, thefte'n .dency for, a bonded composition to absonb'moisture from agent, such that weld. chemistry has. a tendency to vary. I

' 13 3 is a diagram of a-submerged-melt welding sc- 1 the atmosphere can' 'resultinhydrogen embritt lement -oi the-metal, resulting inpoopimpaetproperties coupled Withbracking. By use of the inventive composition; the

difficulty of hydrogen embrittlement is considerably: re- 7 b much less'absorption'of moisture, Suchis theicase beduced, because. exposure to the atmosphere resultswin cause the particles areiused and are of a homogeneous consistency. i

Prior commercially available welding lluxes ot the bonded: bonded alloy types for-joining high-impact capable. ofaccepting supplementary weld-alloy additions such as nickel and the oxides of chmomiurn and molybdenum; i j

' The preferred granular composition accordingto,

invention-is composed of: Material In the drawings:

FIGS. 1 and 2' are graphical representations of impactstrength vs. temperature or various welds; and,

upilllwstrating the invention;

a function of the temperature at which testing/is per.-

steels do not perform satisfactorily with multipower weld- 1 ing. Such welding practices are utilized when it is desired exhibit their-maximum energy absorption levels at room temperature and. above. At lower temperatures impact resistance decreases. During such change in the impact properties of steel, thene exists a temperature range wherein-a' transition from ductile to brittlelfailure exists. 'Such temperature is a useful index to metallurgists, since .steel subjected to. impact loads at and below the transition temperature can fail suddenly and catastmphically.

. A'x further consideration in an examination of impact properties is the effect of thedesired tensile levels uponattain Mechanized srubweight The notch toughness or-irnpact resistance ofsteel trols impact properties.

'weldin'g. V maintain good weldability by adding other constituents;

' when studying impact resistance levels.

The development of fused welding compositions for producing steel welds with high-impact properties must proceed largely along empirical and intuitive lines, because little is known scientifically exactly as to what con- Weld metal chemical analysis is a factor, but identical analyses can occur in welds with totally different impact properties. Likewise, grain size and microstructure of the weld are factors, but steels which from observation and analysis appear identical in all or most other respects still differ widely in impact properties. 1 s

Wollastonite, as suggested by US. Patent No. 2,269,167, has beenused with some success as a principal constituent for arc weldingrod coatings and has also, with some limited success, been applied to welding fluxes for submergedarc welding. In the latter case, such welding compositions as heretofore formulated have lacked desirable welding characteristics while at the same time exhibiting good, but not completely adequate, impact properties such as those desired for present day commercial demands. Our way of approaching a solution to the pro Item is to vary the welding composition by changing the CaOzSiO; ratio. These two constituents occur in the mineral Wollastonite, or calcium metasilicate, CaSiO which has a nominal stoichi-onietric' CaOzSiO ratio by weight of approximately 0.93. I In addition to obtaining good impact properties in the weld metal, a' concomitant problem in the development of a satisfactory composition is to maintain good Weldability in the use of the composition. In other words, the composition, to be useful should produce welds free from surface and other defects and the welds must have position -formulatio-nare principally governed in an essentially binary system by the limit atwhich the material'no longer can be made to lend itself to favorable Outside such limit, it becomes necessary to As 'a result of such judicious and perhaps fortuitous addition,-. the CaO :SiO ratio can be changed if the newly added constituents contribute to improved weldability,

without at the sometime introducing excessive detrimen- A searn'weld 25 in the work 14 is thereby produced. I 1

The mechanical impact properties of several welds were evaluated for steel compositions providing two different tensile levels; namely, 75,000 psi. and 100,000 p.s.i.. In; so doing, all compositions (including the inventive fused composition) tested at the 75,000 psi. level used a suitable, commercially available steel welding electrode of the manganese-molybdenum type. For the tensilelevel of 100,000 p.s.i., specialalloy welding electrodes of the manganese-molybdenum-nickel type were used.

a As shown inFIGf 3, in our process anelect'rode ltl of rod or'wire is drawn by a feed motor 11 from a reel- 12 and fed toward the work 14 as welding current from a a power source 16 melts the 'end of such electrode and adjacent work metal under a blanket l8of granular composition. The latter is delivered to the welding site by a pipe 20 from a hopper 22 containing a supply 24 thereof.

The impact resistance of such welds was measured in terms of the ability of a welded joint to absorb a sudden blow of unusual intensity without failure. The standard Cl'rarpy' V notch impact test provided a'basis for measuring this mechanical property of the welded joint.

FIGS. 1 and 2 trace a family of impact vs. temperature curves for (1) the preferred fused inventive composition (Trace B),' (2) two other experimental fused compositions (TracesA and C), (3) the best prior standard commercially available fused composition, Grade (Trace F), and (4) two prior'commercially available bonded compositions (Traces D and E). An energy absorption level-(broken line 26) of115 ft.'/lb. is shown,

as the specified reference of transition temperature level to brittle fracture. Q

As shown in FIG. 1, for steelsgof 75,000 psi. tensile strength, the energy level of curve A forwelds made with one composition is considerably greater than that with the other compositions tested. Said composition is the upper limit extensively investigated within the range of thefused compositions under consideration. 1 Its CaOzSiO ratio of 1.8 is greater than that of the other compositions including the one corresponding to curve B at a' ratio of 1.06which is the preferred composition. Oomof the preferred i composition.

The preferred inventive composition (Trace B), ha ving a CaOzSiO ratio-of 1.06 produced welds which exhibited very favorable energy absorption levels with con-'' sistently good welding characteristics. Impact resistance values with this preferred inventive composition atO degs. F. are double that of thestandard commercially available fused composition (Trace F), and are about50percent higher than that of tions (TraceD)...

The transition temperature range leading from ductile w into brittle fracture ('asrepresented "by the extended broken lines) for the preferred composition (Trace B) and the extra high CaO:SiO modified composition] (Trace -A) occurs at significantly lower temperatures than thosefor the other compositions studied. The. curve. U preferred for the inventive composition (Trace B)"doe's not intersect the 15 ft./lb.1level even at temperatures as low as de'gs. F. This composition has much better impact properties than the commercially available bonded and fused compositions (Traces D, B, F.) 7 FIG. 2 traces a family of curves similar to that offFIG. '1, but taken at the 100,000 psi. tensile level. Generally,

the curves reflect an overall decrease in the impact level .as compared with the lower tensile level of 75,000 p.s.i. 7

Nevertheless, V the compositions maintain their relative positions;

Thus, it can be seen that impact'prop'erties of' the weld joint sharply increase under the conditions prevail ing in the testing as the ratio :of cao;sio advances from 0.8 to 1.8. The excess CaO present just above the stoichiometric ratio of 0.933 up to perhaps reappears to beof -greatest benefit.

' Optimum impact properties are obtained within 5p ferred CaO content range of atom-3310 55 percent, and

' an-SiO range of fromBO to 45 percent. Generally, 'de-..', sirable impact resistance and good weldability are do velope-dfl'whensuch constituents are present along with may be'somewhatenhanced. Less Ca'OQ than thatjindicated produced lower impact properties in the weld. 5, j Cr'y olite (Na3A1F6) is preferred as the source o f-fluoride the commercial" composi the alloy content of the weld metal."

such oxidesis made primarily to increase tensile strength.

for'the inventivecomposition. For example, when 8 percent cryolite is tested as a part of the inventive composition, impact values at 1()() degs. F. are greater than those obtained with the composition using 6.8 percent Theoptimum cryolite content range is from 4 to r15 percent of the total composition. Above this limit, the weldability of the composition is impaired; while with a lowerfamount, the composition impact resistance properties are impaired. i

. .To again "improve the weldability ofithe composition insofar; as. withstanding undesirable weld 'pocking and porositygMn Q is added to the composition. Wehave found that favorable Welding characteristics are" obtained when the MnO content range varies from between 2 and 10 percent,

The addition of titanium oxide to the inventive c mpositiontends to impair the low. temperature impact prop- In the lightof study made with such additives to the inventive composition, the chromium oxide content should not exceed 1 percent, whereas the molybdenum oxid I level should not exceed percent.

In considering the reasons behind the exceptionally superior'performance of the inventive composition, the combination of the various elements in the inventive composition which yield favorable properties has been arrived at empirically. The precise mechanism, however, which yields the most favorable impact resistance-properties is not understood by us. Nevertheless, welds made with the inventive composition were compared to the basic slagmaking operation inopen hearth steel production.

Reactions "such as desulphurizingand dephosphorizerties'of the weld metal when added in excessof 10 percent. Roomtemperature impact properties, however,

are improved with such additions?Additions'ranging from 5 to ll) percent appear to be beneficialwith regard free of titanium oxide, however, are less costly and have excellent impact properties at room and. lower tempera-f tures. The oxides of'm agnesium and iron appearto' be deleterious and should be controlled such that their maxi mum values are no more than Fpercent each; whereas,

i to room temperature properties rwi'thout adversely afiecting low temperature properties. Compositions essentially aluminum oxide can be tolerated up'to percent of the 7 total. a

Some commercial submerged-arc welding compositions are produced by bonding selected oxides of cal'cium,:silicon, magnesium, manganese, aluminum, Zirconium, and titanium with sodium silicate; However, contrary to such accepted practice with such bonded compositions,

we have found that'any discrete amountsof sodium oxide or sodium silicate within the fused inventive composition does not enhance, but rather adversely affects the impact resistance of the weld metal. with this in mind, the inventive composition has as its upper limit 0.50 percent sodium oxide. Though certain prior commercially available compositions contain greater; amounts of sodium,

oxide or sodium silicate, we have found that optimum impact re'sistance properties'are obtained infused compositions keeping such constituents at low levels. I The preferred andrange of ingredients of the inventive composition are notedbelow; f.

Preferred, percent QaO 44,,Rati0 1.07;.- 33 to S102 41 30 to 45.

' 2t0 6. 4 to 15. Trace10.,

- Trace lKMaxJ. Trace-1 (Ma n).

Trace-2 (Max). Trace-0.5 (Ma-in).

Selected amounts of chromium and molybdenum oxides may beyadded (by tusiori) to the composition, without departing from our invention, order to adjust The addition of In like manner, powdered nickel ranging" from 1 to"'4 percent may be added by bonding to the inventive-com positionwith sodium silicate to aifond higher tensile levels.

'- 3??? m a submerge'daarc welding high-impact steels to produce high impact low temperature welds; said composition being oom-posed mainly of CaO, SiOg, with lesseramounts of V MnO;"2%-8% fluoride; and a trace to 10% TiO said purities,-se1ected from the class consisting of FeO, MgO,

ing occur in the fusiontwelding process of steel. The

class of highly basic welding'oompositions, of which the 1 inventive composition is one, enhances the dcsulphurizing reaction forit is known that high basicity is essential to any extensiveelimination of undesirable phosphorus and sulphur. But, sulphur and phosphorus, in amounts maintained during welding operations carried out by us,

do not appear to be correlated in any way to the results.

of such tests. Consequently, we cannot assume from our data that such constituents are significant governing factors, wherein favorable impactproperties are obtained I with the inventive composition. p I

, Since the inclusions in weld metal are principally silicates, it is reasonable to expect that, when an appreciable lowering of the silicon content in the weld metal is realized, as with the inventive composition, a corresponding significant alteration in either silicate inclusion chemistry or microscopic dispersion within the weld has taken place. That this theory may have pertinent validity can be deduced firom the data noted below wherein the silicon content varies from 10 to 20 points lower in that of the inventive composition as compared with a commercially V available fused composition providing normal impact resistance properties. 7 I

invention preferably is in the form of grains all of which are capable of passing through a No. 12 Tyler screen.

For AC. and position D.C. welding according to the invention, all of the grains should be through a No; 48 Tyler screen.

What is claimed is: a '1. {A fused submerged-melt welding composition for capable of passing CaO ranging between 33% and 55%, the SiO between 30% and 45% and the MnO between.2% and 6%.

0.80 to 1. 8, thereby improving the resulting weldment in high-impact steel. 7

3. Afused submerged-mel-twelding composition as defined byclaim 2.,-.composedof 44%fCaO, 41% SiOg, 4%. MnO, 4% fluoride, 0.1% TiO less than 5% oxide im- 7 A1203, and. N320. I

' I '4. A fused granular submerged-melt welding flux for! submerged-arc welding having relatively high-impact For D.C. downhand welding the composition of the properties even at relatively low temperatures, which is composed of the following:

CaO; 44%. v sio 41%. Mn'O- 4%. Cryo-lite 8%. r TiO Trace-l% (max.). V R90 Trace- 1% maX.). MgO Trace-1% (max.). A1 0 i Trace--2% (max). Na O Trace-0.5% (max.).

5. A fused granular submerged-melt welding compositionfor making steel welds having relatively high impact properties even at relatively low temperatures, which 15 I is composed of the following: i

7 Material; 7 o Range CaO a 33 to 55%. SiO -i 30 to 45%. MnO Zto 6%. cryolite 4it015% TiO Trace-10%.

FeO Trace-4% (max.).

Material: I I a Range MgO Trace1% (max.). A1 0 Trace2% (max.). Na O Trace-0.5% (max).

in the forrn of grains all of which are capable of passing through a No. 12 Tyler screen.

6. A fused granular submerged-melt welding flux as defined by claim 5, in which all of the grains are capable of passing through a No. 48-Ty1er screen.

7. Submerged-arc welding of high-impact steel which comprises feeding aconsumalble steel'electrode toward. 7 the work-in-circuit to be weldediunder a: blanket of fused granular submerged-melt welding composition as defined by claim 6 in which the CaO/SiO ratio ranges between 0.80and1.8. a i

References Cited the fileof this patent UNITED STATES PATENTS 2,200,737' I Clapp May 14, 1940 2,228,639 Miller Ian. 14, 1941, 2,927,990 Johnson Mar. 8, 1960 3,022,413

Johnson Feb'. 20, 1962- 

